In the v3 product variations controller, we register a generate endpoint that does not appear to be covered by the rest api docs.

https://github.com/woocommerce/woocommerce/blob/038e0e910fa415c386f37da04c38e9d61fff3039/plugins/woocommerce/includes/rest-api/Controllers/Version3/class-wc-rest-product-variations-controller.php#L40-L67